In large part, food consumption is driven by pleasure, not just by the need for calories. According to the NIH strategic plan for obesity research, one reason for rising obesity rates may lie in abundant choices of relatively inexpensive calorically-dense foods that are convenient and taste good. That is, many people prefer this type of food stuff as is evidenced by the nearly 2/3 of adults in the United States that are overweight or obese. Overweight and obesity are leading causes of hypertension, stroke, heart disease, chronic musculoskeletal problems, and type 2- diabetes. A well-known fact is that learning plays an important role in the establishment and strengthening of food preferences. Even in adults, though, neural mechanisms exist to dynamically modulate gustatory preference. The objective of this project is to understand changes in gene expression in central gustatory/visceral nuclei that are associated with altered taste preference. The long-term objective is to elucidate neural mechanisms by which the brain integrates orosensory and postingestive signals critical for the establishment of taste preference/aversion behavior. We already know that the gustatory parabrachial nucleus (PBN) is obligate for the expression of learned and some forms of unlearned control of taste preference. Accumulating evidence suggests further that the axons necessary for altering taste preference relay through direct projections from the PBN to ventral forebrain regions like the lateral hypothalamus (LH) and amygdala. The first goal of the current proposal will use DNA microarray analyses to identify genes in the PBN, LH, and amygdala that are up- or downregulated following acquisition of a learned taste preference and learned taste aversion. Thus, new information will be provided concerning genomic correlates of a learned preference that increases consumption and a learned aversion that decreases consumption. The second goal of the current proposal will validate and further quantify changes in gene expression using quantitative real-time polymerase chain reaction (qRT-PCR) as well as Western blot to determine whether changes in mRNA levels are translated into altered protein levels. The third goal will use in situ hybridization to demonstrate that mRNA identified by microarray analysis and validated by qRT-PCR and Western blot is indeed expressed in the brain regions of interest.